Wndproc

This is a discussion on Wndproc within the Windows Programming forums, part of the Platform Specific Boards category; I couldn't understand how WNDPROC(in WNDCLASS) works. How can i make a callback function similar to that? Please advice....

  1. #1
    Unregistered
    Guest

    Question Wndproc

    I couldn't understand how WNDPROC(in WNDCLASS) works. How can i make a callback function similar to that? Please advice.

  2. #2
    Registered User
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    Jun 2002
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    267
    You'll have to re-phrase that question to get a decent response

  3. #3
    Raven Arkadon
    Guest
    LRESULT CALLBACK my_wndproc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam) {
    switch(msg) {


    }

    return ;
    }



    WNDCLASS wndclass;
    memset(&wndclass, 0, sizeof(WNDCLASS));
    ...
    wndclass.lpfnwndproc = my_wndproc;

  4. #4
    Registered User
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    244

    Angry

    ARGH! i accidently posted the unfinished reply... AND I COULD'NT EDIT IT... >_<

    ok, again:

    //this is your wnd proc
    //whenever your window receives a message, this function will be called (as long as you call DispatchMessage( ... )
    LRESULT CALLBACK my_wndproc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam) {
    switch(msg) {
    //handle the message
    }
    }

    return 0; //hm... should we return 0 if we processed the message or if we didn't? --- i am not sure now but you can rtfm
    }



    WNDCLASS wndclass;
    memset(&wndclass, 0, sizeof(WNDCLASS));
    ...
    wndclass.lpfnWndproc = my_wndproc; //every window created with this windowclass will have my_wndproc as it's window procedure.

    so thats how to declare a callback function
    signature under construction

  5. #5
    Unregistered
    Guest
    Thanks, Raven Arkadon.
    I know how to program using the WNDCLASS. I wanna know what's behind the WNDCLASS and WndProc. How can i make a call back function which has the same 'magic' as WndProc?

  6. #6
    &TH of undefined behavior Fordy's Avatar
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    Originally posted by Unregistered
    Thanks, Raven Arkadon.
    I know how to program using the WNDCLASS. I wanna know what's behind the WNDCLASS and WndProc. How can i make a call back function which has the same 'magic' as WndProc?
    The WNDCLASS is just a structure of information sent to RegisterClass to allow you to create windows using those styles.....

    The WndProc is a simple call back that can be defined however you want as long as it's declared. You include a pointer to this function in your WNDCLASS

    Code:
    LRESULT CALLBACK my_wndproc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
    Meaning a function that recieves 4 32bit params. It returns an LRESULT and as a callback, allows the system to call it....

    That's all that's needed.......the rest you can define yourself

  7. #7
    Carnivore ('-'v) Hunter2's Avatar
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    I wanna know what's behind the WNDCLASS and WndProc. How can i make a call back function which has the same 'magic' as WndProc
    I think that means "how do you use function pointers"...

    Try this site:
    http://www.function-pointer.org/
    Last edited by Hunter2; 08-12-2002 at 08:28 PM.
    Just Google It. √

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